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A natural language interface (NLI) to databases is an interface that translates a natural language question to a structured query that is executable by database management systems (DBMS). However, an NLI that is trained in the general domain is hard to apply in the spatial domain due to the idiosyncrasy and expressiveness of the spatial semantics. Moreover, there are a wide range of database servers available, and a unilingual NLI model limits its practical usage. In this article, we propose to not only address the spatial domain generalization challenge, but also support multilingual back-end, i.e., supporting different query languages, such as SQL and Prolog. For the challenge of spatial semantics, we propose a spatial comprehension model that is able to recognize the meaning of spatial entities based on the semantics of context and effectively resolve the ambiguity given the spatial semantics. The spatial semantics learned from the spatial comprehension model is then injected to the natural language question to ease the burden of capturing the spatial-specific semantics. We also propose to add a prefix symbol to support the multilingual back-end (e.g., query languages). With our spatial comprehension model and symbol injections, our NLI for the spatial domain, named SpatialNLI, is able to capture the semantic structure of the question and translate it to the corresponding syntax of an executable query accurately. We also experimentally ascertain that SpatialNLI outperforms state-of-the-art methods. [ABSTRACT FROM AUTHOR]

As an intermediate category between metric and topology, directional relations are as much varied as 'right of', 'before', 'between', 'in front of', 'back', 'north of', 'east of', and so on. Directional relations are ambiguous if taken alone without the contextual information described by frames of reference. In this paper, we identify a unifying framework for directional relations and frames of reference, which shows how a directional relation with its associated frame of reference can be mapped to a projective relation of the 5-intersection model. We discuss how this knowledge can be integrated in spatial query languages. [ABSTRACT FROM AUTHOR]

Current database systems cannot only store standard data like $\underline{integer}$, $\underline{string}$, and $\underline{real}$ values, but also spatial data like $\underline{points}$, $\underline{lines}$, and $\underline{regions}$. The importance of topological relationships between spatial objects has been recognized a long time ago. Using the well known 9-intersection model for describing such relationships, a lot of different topological relationships can be distinguished. For the query language of a database system it is not desirable to have such a large number of topological predicates. Particularly the query language should not be extended by a lot of predicate names. It is desirable to build new relationships from existing ones, for example to coarse the granularity. This paper describes how a database system user can define and use her own topological predicates. We show algorithms for computing such predicates in an efficient way. Last, we compare these general versions with specialized implementations of topological predicates. [ABSTRACT FROM AUTHOR]

One of the most important queries in spatio-temporal databases that aim at managing moving objects efficiently is the continuous K-nearest neighbor (C KNN) query. A C KNN query is to retrieve the K-nearest neighbors ( KNNs) of a moving user at each time instant within a user-given time interval [ t s , t e ]. In this paper, we investigate how to process a C KNN query efficiently. Different from the previous related works, our work relieves the past assumption, that an object moves with a fixed velocity, by allowing that the velocity of the object can vary within a known range. Due to the introduction of this uncertainty on the velocity of each object, processing a C KNN query becomes much more complicated. We will discuss the complications incurred by this uncertainty and propose a cost-effective P2 KNN algorithm to find the objects that could be the KNNs at each time instant within the given query time interval. Besides, a probability-based model is designed to quantify the possibility of each object being one of the KNNs. Comprehensive experiments demonstrate the efficiency and the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Topological relationships like overlap, inside, meet, and disjoint uniquely characterize the relative position between objects in space. For a long time, they have been a focus of interdisciplinary research as in artificial intelligence, cognitive science, linguistics, robotics, and spatial reasoning. Especially as predicates, they support the design of suitable query languages for spatial data retrieval and analysis in spatial database systems and geographical information systems. While, to a large extent, conceptual aspects of topological predicates (like their definition and reasoning with them) as well as strategies for avoiding unnecessary or repetitive predicate executions (like predicate migration and spatial index structures) have been emphasized, the development of robust and efficient implementation techniques for them has been largely neglected. Especially the recent design of topological predicates for all combinations of complex spatial data types has resulted in a large increase of their numbers and stressed the importance of their efficient implementation. The goal of this article is to develop correct and efficient implementation techniques of topological predicates for all combinations of complex spatial data types including two-dimensional point, line, and region objects, as they have been specified by different authors and in different commercial and public domain software packages. Our solution consists of two phases. In the exploration phase, for a given scene of two spatial objects, all topological events like intersection and meeting situations are summarized in two precisely defined topological feature vectors (one for each argument object of a topological predicate) whose specifications are characteristic and unique for each combination of spatial data types. These vectors serve as input for the evaluation phase which analyzes the topological events and determines the Boolean result of a topological predicate ( predicate verification) or the kind of topological predicate ( predicate determination) by a formally defined method called nine-intersection matrix characterization. Besides this general evaluation method, the article presents an optimized method for predicate verification, called matrix thinning, and an optimized method for predicate determination, called minimum cost decision tree. The methods presented in this article are applicable to all known complete collections of mutually exclusive topological predicates that are formally based on the well known nine-intersection model. [ABSTRACT FROM AUTHOR]

Existing estimation approaches for spatial databases often rely on the assumption that data distribution in a small region is uniform, which seldom holds in practice. Moreover, their applicability is limited to specific estimation tasks under certain distance metric. This paper develops the Power-method, a comprehensive technique applicable to a wide range of query optimization problems under both L ∞ and L 2 metrics. The Power-method eliminates the local uniformity assumption and is, therefore, accurate even for datasets where existing approaches fail. Furthermore, it performs estimation by evaluating only one simple formula with minimal computational overhead. Extensive experiments confirm that the Power-method outperforms previous techniques in terms of accuracy and applicability to various optimization scenarios. [ABSTRACT FROM AUTHOR]

In this paper a visual approach to querying in spatial databases is presented. A filter flow methodology is used to consistently express different types of queries in these systems. Filters are used to represent operations on the database and pictorial icons are used throughout the language for filters, operators and spatial relations. Different granularities of the relations are presented in a hierarchical fashion for spatial constraints. The language framework and functions are described and examples are used to demonstrate its capabilities in representing different levels of queries, including spatial joins and composite spatial joins. Here, the primary focus is on the query language itself but an overview of the implemented interface of the language is also provided. [ABSTRACT FROM AUTHOR]

Spatio-temporal databases deal with geometries changing over time. In general, geometries cannot only change in discrete steps, but continuously, and we are talking about moving objects. If only the position in space of an object is relevant, then moving point is a basic abstraction; if also the extent is of interest, then the moving region abstraction captures moving as well as growing or shrinking regions. We propose a new line of research where moving points and moving regions are viewed as 3-D (2-D space+time) or higher-dimensional entities whose structure and behavior is captured by modeling them as abstract data types. Such types can be integrated as base (attribute) data types into relational, object-oriented, or other DBMS data models; they can be implemented as data blades, cartridges, etc. for extensible DBMSs. We expect these spatio-temporal data types to play a similarly fundamental role for spatio-temporal databases as spatial data types have played for spatial databases. The paper explains the approach and discusses several fundamental issues and questions related to it that need to be clarified before delving into specific designs of spatio- temporal algebras. [ABSTRACT FROM AUTHOR]

A spatial query language called SQL/Spatial has been designed to support the expression of user requests dealing with a variety of GIS analysis functions (e.g., map overlay and buffer) in the Web environment. Using the familiar SELECT - FROM - WHERE statement instead of procedural commands like macro language in some GIS packages, users can formulate their queries more easily, while conducting powerful spatial data retrieval and analysis. The language investigates an appropriate structure to express spatial queries within the framework of the on-going SQL standards for spatial extensions (i.e., Open GIS Simple Features Specification for SQL and SQL3 MultiMedia Specification Part 3: Spatial). By restructuring the FROM clause via a subquery, SQL/Spatial is well adapted to the general spatial analysis procedure by using current GIS packages, while conforming well to the SQL design concepts. The interface (client) of the language resides with a Web browser, while the query is processed by a query server. The query server, linked to the Web server via Common Gateway Interface (CGI) scripts, is composed of a query processor, Spatial Database Engine (SDE) and MapObjects Internet Map Server. It was demonstrated that the design of SQL/Spatial facilitates the access to spatial analysis functionalities on the Web. [ABSTRACT FROM AUTHOR]

Introduces research papers about spatial and computational intensive research published in the 1999 issue of "GeoInformatica." Retrieval of graphical images using cluster content-based wavelet selection process; Proposal for a speculative model as an extension of an infrastructure for distributed databases; Design a spatial query language for the accommodation of spatial analysis functions in the Web environment; Use of a combination of spatial clustering and graph theories for the simplification of road junctions during generalization.